Pornography websites should require users to prove they are over the age of 18, a UK industry regulator has said.

Atvod, the Authority for Television on Demand, said laws should be changed to protect children from viewing graphic adult material online.

Research for Atvod found that 6 per cent of children aged 15 or under had accessed an adult website over the course of a month, the BBC reported.

Some 5 per cent of visitors to adult sites were under 18, while the website Pornhub was visited by 112,000 boys in the UK aged between 12 and 17.

The statistics were uncovered after the online habits of 45,000 desktop computers and laptop users were monitored over a month, with volunteers reflecting a cross-section of the population.

Atvod said the issue of children accessing online pornography was so urgent that it was "critical the legislation is enacted during this Parliament”.

And it said sites that did not comply with age checks should be forbidden from processing payments from British customers.

Currently, Atvod forces pornographic websites based in the UK to carry out age verification checks before customers can view explicit photographs or video, the BBC said, by requiring valid credit card details or personal information that can be checked.

But it said the vast majority of online pornography was downloaded from overseas businesses, over which it has no control.

Atvod wants all adult sites to request a licence which would be granted on the condition that age checks were in place, with credit and debit card operators not allowed to handle fees for services from UK citizens to unregistered sites

Atvod chief executive Pete Johnson told the BBC: "We're a very substantial market and to access the money that's flowing from the UK would be quite a powerful incentive to introduce restrictions."

An Atvod spokesman added: "The material that appears on the free services is placed there by the paid services to attract customers to sign up to subscriptions.

"As long as the paid service placed content on a free service without age verification it would be in breach of its licensing conditions and so would not be able to access funds from the UK.

"We're not saying this will stop all children seeing all pornography online.

"But our argument is that even if you reduce the number of children who are accessing hardcore pornography online by 10 per cent, that would be a significant win."

The Government has already put pressure on internet service providers to roll out so-called porn filters that automatically block adult content unless households specifically opt out.

The four major ISPs - BT, Virgin, Sky and TalkTalk - have all introduced such filters.